In the toroidal transformer design disclosed in U.S. Pat. No. 4,779,812, dated Oct. 25, 1988, which is a continuation of application Ser. No. 06/705,045 filed June 27, 1985, now abandoned, entitled "Toroidal Electrical Transformer and Method of Producing Same," this application being a continuation of 06/337,356, filed Jan. 6, 1982, now abandoned and in a copending Application Ser. No. 06/662,312, filed Oct. 17. 1984, entitled "Apparatus And Method For Fabricating A Low Voltage Winding For A Toroidal Transformer," now U.S. Pat. No. 4,665,952 a core wound of a single continuous strip of magnetic material is surrounded by two arcuate coil assemblies, each having a high voltage winding and a low voltage winding, and each being of a substantially continuous conductor. Each arcuate coil assembly extends over approximately 165.degree. of the toroidal core leaving a space between the two coil assemblies of approximately 30.degree. (32.degree. in one preferred embodiment). Two like-size, wedge-shaped spacers are mounted in these spaces to separate the two coil assemblies. Accordingly, each space is approximately 15.degree. (16.degree. in one preferred embodiment).
In the final assembly of the toroidal transformer, it is necessary to support the coil assemblies with respect to the core and transformer tank so as to prevent movement and consequent damage to the coil assemblies during transportation and operation of the toroidal transformer. In the above-referenced application, this was accomplished by a pair of butterfly-shaped core blocks which were inserted between the coil assemblies, one from the bottom and the other from the top of the toroidal transformer assembly. The butterfly-shaped core blocks had wings of approximately 15.degree. (16.degree. in one preferred embodiment) to correlate with, and fill the space between the two coil assemblies. The two butterfly-shaped blocks had a rectangular cut-out in each wing which accommodated the core and which were contiguous at the centerline of the toroidal transformer.
In the above-referenced applications, the teachings of which are incorporated herein by reference thereto, the butterfly-shaped core blocks were fabricated from a moldable-polyester resin. The moldable-polyester resin had the advantage of being a dielectric, so as to not present the risk of a short circuit of the transformer windings, and also had the characteristic of being non-magnetic, so as to obviate any interference with either the performance characteristics of the transformer or its operation through interaction with the magnetic flux generated within the transformer as a result of the energization of the electrical windings of the transformer.
Each of butterfly-shaped core blocks of the above-referenced applications, while having the above advantages and being suitable from a functional standpoint, was relatively expensive because polyester resins suitable for use in transformers are relatively expensive. In addition, the strength of the structure was limited by the available space for the core block which in turn limited the size of the core block. Given the inherent structural integrity of the moldable-polyester resin, its strength was limited due to the rather confined space between the two coil assemblies. Additionally, the butterfly-shaped core block of the above-referenced application had a disadvantage in that oil or coolant flow passages could not be provided without adding substantially to the complexity of the mold necessary to form such coolant passages and without compromising the strength of the core block as a result of the voids provided by the coolant passages.